mineral

Moonstone

Orthoclase/Albite (KAlSi3O8 / NaAlSi3O8) with Adularescence

Hardness: 6.0-6.5 (Mohs scale), Color: Colorless to white with blue/silvery sheen, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Two directions at 90 degrees, Specific gravity: 2.56-2.59

Hardness: 6

Identified February 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks through the slow cooling of magma where orthoclase and albite layers intergrow and then separate during cooling, creating an internal structure that scatters light. Found in pegmatites and alpine-type veins.

Uses & applications

Primarily used in jewelry for cabochons and beads due to its unique optical effect (adularescence). Also popular for metaphysical and mineral collecting.

Geological facts

The blue sheen, known as adularescence, is caused by the interference of light as it passes through thin, alternating layers of orthoclase and albite. It is the Florida State Gemstone (honoring the moon landings despite not being found there).

Field identification & locations

Identified by its characteristic milky appearance and pearly blue shimmer when tilted under light. Commonly found in Sri Lanka, India, Myanmar, and Madagascar. Look for the distinct flash against a white or colorless body.

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